Portable apparatus for boring plug seats and the like



Feb. 4, 1941. c Q LENARTH 2,230,509

PORTABLE APPARATUS FOR BORING PLUG SEATS AND THE LIKE Filed Oct. 29,1958 2 Sheets-Sheet 1 FIGI CLARENCE C. LENARTH fi ENTOR Feb. 4-, 1941. QQ LENARTH 2,230,509

PORTABLE APPARATUS FOR BORING PLUG SEATS AND THE LIKE Filed Oct. 29.,1938 Sheets-Sheet 2 CLARENCE CLENARTH INVENTOR Patented Feb. 4, 1941UNITED STATES PATENT OFFICE PORTABLE APPARATUS FOR BORING PLUG SEATS ANDTHE LIKE 1 Claim.

It is often the case that in permanently installed apparatus there areconical valve or plug seats which, from time totime, are in need ofreboring. An example of this is in the junction boxes of certain oilrefinery still furnaces, which are provided with removable plugs inorder that the interior of the tubes be accessible. Since it is requiredthat these plugs prevent leakage of petroleum at high temperature andunder considerable pressure, it is necessary that plugs and seats bemachined to a precise fit and while the plugs may be taken to a machineshop, the plug seats are in heavy, integrally cast manifolds which maybe removed from the furnace structure only with great difficulty.

The object of my invention is to providea portable machine, capable ofmicrometric precision, for reboring such plug seats.

Another object of my invention is to provide means for accuratelyplacing this machine with relation to the work.

A further object of my invention is to provide automatic feed means forprogressively changing the position of the cutting tool during boring.

Further objects of my invention will appear from a consideration of thefollowing description and of the attached drawings in which:

Fig. l is a view in elevation and section of my device in position at ajunction box. Certain hidden portions are shown by broken lines and theupper portion is broken off.

Fig. 2 is a View in elevation and section of the upper portion of mydevice. Figs. 1 and 2 are continuations of one another (a portion beingduplicated for additional clarity) and are shown separately solely forthe purpose of avoiding undue crowding of the drawings and of thereference numerals.

Fig. 3 is a View taken as indicated by the line 3-3 of Fig. 2.

Fig. 4 is an end View of the lower end of my device, the junction box H)of Fig. 1 being omitted.

My device is capable of operating in any position; it is illustrated inthe drawings as being disposed vertically solely for convenience, inactual practice it will more often be placed horizontally.

Referring to the drawings, I represents a portion of the junction boxmanifold, provided with the conical plug seat II. and ears l2-l2. Theseears are for the purpose of holding a screw yoke by which a plug issecured tightly in place in the plug seat, but they are used inconnection with my invention as means of supporting the boring machine.

The spider body I3 is provided with a plurality of radial threadedopenings adapted to receive the adjusting and supporting legs I l-44.For

convenience in making the adjustments I prefer to arrange these legs intwo whorls of four each, though it would be possible to use anyarrangement which is capable of holding the spider body both in linewith and centrally with respect to the plug seat I I. Means for makingthe measurements necessary for the adjusting will appear hereinafter.

Spider body I3 is also provided with a coaxial opening which holds thebushing l5; this bushing serves as the bearing for the entire rotatableportion of the machine. I have found it desirable to provide means ofadjusting this bushing in order to eliminate all tendency to chatter. Itis therefore slotted along three sides of a rectangle, as shown inbroken lines, and screws l6lfi are provided adapted to force therectangular portion of the bushing with any desired degree of pressureagainst the journal portion I! of the boring bar generally indicated at!8-l8.

Boring bar it is a unitary piece comprising the head l9, the journal H,the threaded portion 24), and the tail 2| as shown in Fig. 2. Fixedlyattached to the boring bar I8 are the double V belt pulley 22 and thecap 23. Coaxial with the boring bar, and running the entire length ofit, is provided a cylindric opening which is enlarged through the headportion.

Head is is provided with guideway 24, which is preferably formed in themanner shown with three plane surfaces intersecting at 60", more orless, and slightly indented portions at the intersections to preventpossible binding. However,the shape of this guideway is not ofimportance, it being required only thatit be precisely straight and atthe angle of the plug seat to be bored, and that it have adequatebearing surface in all directions for the tool holder 25 which is theguided member. Communicating between giudeway 24 and the central openingof the boring bar is radial slot 26, shown in Fig. 4.

Tool holder 25 is adapted to fit closely but slidably in guideway 24,and is provided with a pair of ears 21-21 which project into slot 25.The tool holder is also provided with one or two holes 28 adapted tohold a cutting tool 29. It is not contemplated that more than one toolbe used at once, the plurality of holes 28 is merely to make the machineadaptable to a greater variation of diameters of plug seats. In orderthat the quality of the fit between tool holder 25 and guideway 24 becontrollable the guideway is provided with take-up strip 30 which iskeyed by pins for motion transverse to the boring bar and which isadjustable by means of screws 3!-3l.

Running in the central opening of head I9 is feed screw nut 32 which isprovided with tongue 33. This tongue projects into the slot '26 andengages accurately the ears 21-21 of the tool holder. Thus, motion ofthe nut 32 lengthwise of the boring bar propels the tool holderlengthwise of the guideway 24. The nut is propelled by tubular feedscrew 34 which runs the entire length of the boring bar through theabove mentioned central opening, and it projects beyond the end of tailportion 2 I. The threaded portion of the feed screw which engages thenut 32 is entirely contained in the boring bar head IS, the remainder ofthe screw is smoothly cylindrical, working a free running fit in theboring-bar, except that the lower end has a threaded portion adapted toreceive the thrust nut 35, and the upper end is provided with a squaredportion and a threaded portion hereinafter described.

Thrust nut 35 is adapted to be screwed upon the end of feed screw 34 andis held fixed by a set screw 36; it is provided with a shoulder 31 whichbears against the outer end of the boring bar thereby resisting thrustin one direction. The opposite thrust is resisted by contact with thecap 23.

It will be seen that normally feed screw 34 will rotate with the boringbar as a unit, there being considerable friction between the two, bothat the thrust nut and throughout the smooth portion of the feed screw.Thus, normally, tool holder 25 will not be moved in relation to theboring bar. However, the feed screw may be forcibly held againstrotation or may be rotated differently than the boring bar, therebymoving the tool holder as desired.

Means for rotating the feed screw with relation to the boring bar, bothautomatically and by hand, are located at the upper end of the machineshown in Fig. 2, and will now be described.

Feed screw 34, immediately above the tail end 2| of the boring box, isprovided with a squared portion to receive a ratchet wheel 38. Thisratchet wheel is provided with a crank 39 for hand operation. Beyond thesquared portion the feed screw is provided. with threads for theretaining nut 43 and for the arm 4| whose function will appearhereinafter.

Fastened fixedly to the upper end of the boring bar, in juxtaposition tothe ratchet wheel 38, is the cam 42, which is an integral partcomprising a short cylindrical body, and the cam proper, which is of theform shown in Fig. 3, circular with a short portion of the peripheryinterrupted. The length of this interruption controls the speed of theautomatic feed. If it is desired that the machine be adaptable tovarious kinds of work requiring different depths of cut, replacementcams may be provided.

A pawl 43 is provided, adapted to be held from engagement with ratchetwheel 38 by cam 42 during the greater part of a cycle of rotation of theboring bar, but drawn into engagement by spring 44 Whenever theinterrupted portion of the cam comes around into position with the pawl.While the pawl is in engagement, the ratchet wheel, and thereby the feedscrew 34, is held stationary against the rotation of the boring bar anddue to the screw action in the head 19, the cutting tool is advanced thedesired distance on the work.

Pawl 43 is carried pivotally by arm 45 which is supported by collar 46,loosely mounted on the cylindrical portion of cam 42. This arm alsocarries kicking strap 41, provided for the purpose of opposing andbalancing the force applied to arm 45 at the time when the pawl engagesthe 7'; ratchet wheel. The eccentric cam 48 (hand operated) is providedfor pushing the pawl out of operative position in order to discontinuethe automatic feed when desired.

Arm 45 is restrained from rotation by means of rod 49 which passesthrough a hole in the outer end of the arm. Rod 49 is most convenientlyattached, as shown, to a bar such as 50 provided for resisting thetension of the driving belts, but can be attached to any object whichdoes not share the rotary motion of the boring box.

Bar 50 is an adjustable member for regulating the tension of the beltsand connects collar 5| with a similar collar on the shaft of the motor,not shown but preferably an electric motor with built-in speed reductiongears.

I prefer using a. double V belt drive because this machine operates atcomparatively low speed (perhaps 50 R. P. M.) against considerableresistance, and a drive with less friction surface would be likely toslip.

The portions of my invention above described are those involved in theactual operation of boring; the remaining portions are those involved inthe operation of placing the machine accurately in position.

The aligning of the machine may be done by simply measuring, as with asteel rule, the distances from the lip of the plug seat to someconvenient portion of the boring machine, such as the belt pulley, andadjusting the legs I4|4 until the distances are the same on all sides ofthe machine. It is advisable, if the belt pulley is to be used for thispurpose, that particular care be taken that its lower edge be accuratelyin a plane perpendicular to the axis of the boring bar. But thecentering ofthe device, which requires micrometric accuracy ofmeasurement, cannot beaccomplished without the greatest of difficultyunless a measuring device be incorporated in the machine. Such a deviceis described in the following paragraphs.

Boring bar head I9 is provided with recess 52 which enters obliquely anddeeply enough so that its floor is slightly beyond (and parallel to) aplane through the axis of the boring bar. On the floor of this recess ismounted the lever 53, to which is attached the spring in tension 54which tends to produce clockwise motion of the lever. Communicating withlever 53 is the gauge rod 55 carried in the bushing 55; the outer end ofthis rod, when in use, is in contact with the plug seat as shown withbroken lines in Fig. 1. Preferably, the axis of rod 55 lies in a planethrough the axis of the boring bar and is perpendicular to the surfaceof the plug seat. However, this position is not strictly necessary.

As the boring bar is rotated, approximately in position and with cuttingtool removed or placed out of contact with the plug seat, rod 55 willmove back and forth in its bushing because of an eccentric effect unlessthe boring bar is perfectly centered. These motions of rod 55 aretransmitted to lever 53, thereby to rod 51 which runs through -alongitudinal hole, thereby to lever 58 which is carried by a supportattached to cap 23, thereby to rod 59 which runs the entire length ofthe machine through the center of tubular feed screw 34, and thereby toa conventional micrometric indicator 85 of the dial type which ismounted as shown on supporting arm 4|. Through this chain of rods andlevers the minute variations in the distance from the 'plug seat to theaxis of the machine are immediately visible to the operator while theboring bar turns.

I have found that if rod 59 has its frictional area reduced as indicatedand if it is kept well lubricated, the pressure of the spring containedin indicator Bil is sufiicient to keep the chain of rods and levers incontact. However, it would be entirely possible to provide a spring forthis purpose, such as a helical spring in compression mounted betweencap 23 and a suitable collar on rod 59 near its end. Whether such aspring is used or not, spring 54 must .be of sufiicient 0 strength tokeep rod 55 in contact with the plug seat. Set screw 6| in bushing 58 isprovided to hold rod 55 retracted from the plug seat after centering hasbeen accomplished. This is desirable in order to avoid unnecessary wear.The centering adjustments indicated as neces sary by the above describedmeasuring device are made by means of legs I l-44, as are the aligningadjustments. One more adjustment means is required, since the depth towhich the boring box is inserted determines the size of plug seat thatmay be bored. Alignment and centering being accomplished and spider bodyI 3 being thus fixed in its proper position, the boring bar may be movedlongitudinally with relation to the spider body by means of bar feed nut62 operating on the threaded portion 28 of the boring bar.

Nut $2 is held at a fixed distance from spider body i3 by means ofsleeve 53 which is provided with an outwardly projecting flange at eachend. An annular recess is formed in the spider body between a shoulder64 and a ring-shaped plate 65; a similar recess is formed in the barfeed nut between shoulder 66 and plate 61. The flanges on sleeve 63 fitclosely in these recesses. Thus as nut 62 is turned upon the boring bar,the spider body being held fixed, the head of the boring bar is pushedinto or drawn from the plug seat.

This lengthwise adjustment having been made, it is necessary that it bepreserved. For this purpose is provided set screw 68 acting upon plug 69which engages the threaded portion 20 of the boring bar, preventingaccidental rotation of the nut 82 with respect to the boring bar. Inorder that the threads not be damaged, the inward end of plug 69 isprovided with a notched surface to fit the threads. As an additionalsafeguard, in order that there be no frictional force tending 50, tomove nut 62, sleeve 63 is keyed, by means of key 10 .and longitudinalkeyway H, for rotation with the boring bar. As a still furthersafeguard, the threads 20 of the boring bar are made lefthanded in orderthat if nut 62 is accidentally 55 engaged by some extraneous objectwhile the bar is rotating, the cutting tool will be withdrawn from thework instead of being forced deeply into it.

Having described the embodiment of my in- 00 vention illustrated in theattached drawings, I will now briefly describe the method of using it.

The machine is placed approximately in position by hand and the spiderlegs M-M are tightened sufiiciently to hold it in place. While this 65is done, the tool holder 25 is preferably kept retracted from the workat or nearly at its limit of motion toward the upper end of Fig. 1, inorder that the cutting tool not impinge on the plug seat duringadjustment.

70 Measurements are then taken with any suitable rule or tape betweenthe lip of the plug seat and the edge of the belt pulley 22 and themachine accordingly aligned with the work by suitable adjustments oflegs i l-M. At this time it is convenient to center the machine asclosely as may be done by rough measurement or visual estimation.

The machine being approximately in position, the belts are placed onpulley 22 and the driving pulley of the motor, and tightened by means ofa length adjustment on bar 50. In this tightening, the motor, which maybe mounted slidably on a suitable track, is the movable member and thetension of the belts is exerted entirely as compression on bar thusthere is no torque on the spider caused by the drive means which wouldtend to pull the machine out of alignment.

Set screw BI is loosened, allowing gauge rod to make contact with theplug seat and to move freely in its bushing 55. Indicator is placed inposition on arm 4! and set at zero reading and the motor is started. Asthe boring bar rotates, its eccentricity in the plug seat is shown byvariations on the dial of indicator it and suitable adjustments of thespider legs lil i may be made to eliminate the eccentricity. At thistime it may be convenient to make the final aligning adjustments also.For satisfactory and economical operation the centering should be donewith an accuracy of the order of a thousandth of an inch or better,which will not be difficult with the apparatus described.

Centering and alignment being accomplished and the motor being stopped,gauge rod 55 is pushed back into its bushing and held retracted bytightening set screw 61. Then longitudinal adjustment is made by meansof nut 82 and the tool holder 2 5 is moved in its guideway by means ofcrank 39 until the edge of the cutting tool is exactly in position atthe lip of the plug seat, ready to begin boring. Then set screw 68 istightened firmly and the motor is started and allowed to run until theboring is completed.

It is to be understood that the particular embodiment of my inventionherein shown and described is susceptible of various changes and Ireserve the right to such modifications as come within the scope of theappended claim.

I claim as my invention:

Portable apparatus for boring conical plug seats and the like,comprising: a rotatable boring bar provided with a longitudinal centralopening and having :a head provided with a guideway disposed at an angleto the axis of said boring bar, said angle being equal to the anglebetween a genatrix and the axis of the conical surface to be bored andprovided with a radial slot communicating between said guideway and saidcentral opening; a tool holder adapted to move in said guideway; a feedscrew adapted to rotate within said central opening and to f-rictionallyengage said boring bar; a nut threadedly engaging said feed screw andhaving a tongue which extends into said radial slot and which isarranged to engage transversely disposed surfaces of said tool holder insuch manner as to transmit longitudinal motion of said nut to said toolholder while leaving said tool holder free to approach and recede fromsaid feed screw; means for rotating said feed screw relative to saidboring bar at intervals; means for maintaining said rotatable boring barcoaxial with the conical surface to be bored and in fixed longitudinalrelation thereto throughout the boring operation; and means for rotatingsaid boring bar.

CLARENCE C. LENARTI-I.

